Apparatus for marking refillable containers, more especially plastic bottles

ABSTRACT

An apparatus is disclosed for marking refillable containers, more especially plastic bottles, with code symbols for later ascertaining whether a container has to be refilled or separated. The part of the container in which is situated a manufacturer&#39;s code present from the outset is photographed at a detection station by a camera. Using code symbols applied previously as a reference marking, the place is determined at which a new code symbol of a round trip code is applied at a marking station with a laser. The number of such code symbols gives the number of fillings of the containers, and the data content of each code symbol contains a statement concerning the filling inserted in the container, the bottler etc., in each case. With the aid of this, a certain filling sequence can be adhered to, for example, prevent a plastic bottle which previously contained a cola drink being filled with mineral water, whereas the reverse sequence would be permissible.

BACKGROUND OF THE INVENTION

This application is a division of Ser. No. 07/893,194, filed Jun. 2,1992, now abandoned.

The invention relates to an apparatus for marking refillable containers,more especially plastic bottles, with code symbols with the aid of whichit can be determined later whether a container has to be filled again orseparated or discarded.

From DE-PS 36 26 775 it is basically known for multiple trip containersto be provided with a supplementary coding during each return. Nosolution is shown here for the problem of arranging the coding so thatit can be detected in as error-free and also space-saving a manner aspossible. The latter is especially important, because the quantity ofdata which has to be introduced onto the container during the life ofthe container, as data concerning the container itself and the filling,is on the increase, and because moreover, ever smaller containers (eg.0.3 liter PET bottles) have to be able to be marked in this way.

From EP-A 354 362 it is known for PET bottles to be provided with codesymbols by means of a laser, and a special code-reading process is knownfrom DE-OS 29 43 811.

DE-OS 30 32 520 describes an arrangement for the control of the lengthof use of cylindrical containers, more especially kegs. Kegs for thedrinks industry require recalibration at predetermined time intervals,eg. after eight years in each case. The known arrangement makes itpossible to control the time of putting cylindrical containers inoperation with regard to the necessity for recalibration of thecontainer. To this end, each container carries in a first imaginarycircle a position marking, with which a first scanning head iscoordinated. In a second imaginary circle, the container carries codesymbols in the form of lines which state the commissioning time, andwith which a second scanning head is coordinated. The container is madeto rotate about its axis of symmetry, and the first scanning headswitches on the second scanning head when the position marking isdetected, in its turn the second head switching on a marking reader. Thecode symbols for the commissioning time are composed of a number oflines, on account of which the scanning head detecting them operateswith a counter, and the number of lines detected represents a measure ofthe commissioning time of the container. Each recalibration is retainedby introducing a new code symbol. Comparison of the counter result witha control value then produces a measure of whether the container beinginspected has been in operation already for a length of time which makesa recalibration necessary. If the necessity for recalibration isdetermined, the relevant container is separated and conveyed forcalibration in another device, in which the new code symbol is alsointroduced. This introduction of the new code symbol takes place in amanner and at a location which are not described in DE-OS 30 32 520.Moreover, the introduction of a new code symbol takes place at anyinterval in relation to the preceding code symbols, which is adequate inthe case of the known arrangement, as the code symbols are merelycounted. The code in the known marking process, which is composed of thecode symbols, obviously does not have a data content extending beyondthe number of recalibrations which have taken place or the years whichhave passed since the commissioning of the container.

From DE-OS 36 23 475 is known a process for the recognition of mainlyrotationally symmetrical objects, more especially containers, which areprovided with code symbols, which process serves to recognise transportcontainers, eg. in the drinks industry, which are provided with anindividualizing marking, from which, amongst other things, the owner andthe commissioning time can be seen, in order to be able to follow thepath of empties. This known process relates less, however, to codeassembly, but more to the removal of the problem of being able to readthe coding reliably when it has no accurately predetermined position inrelation to an optical sensor. In order to remove this problem, the codesymbols in the known process are arranged as radially running bars witha luminance factor differing from the surroundings, the bars beingdisposed circularly around a centre point. The bars are scanned, andfrom the scanning signals a mean value is obtained. The signals arebinarized using a threshold value derived from the mean value, and thebinary signals are decoded. The circular ring of the code symbols ishere divided into identical sectors provided in each case for one codesymbol, and a certain number of sectors is provided for representing onepoint of a data word in each case. In this known process, it is neitherintended nor possible to mark containers with new code symbols, with theaid of which it might later be ascertained whether a container has to berefilled or discarded.

In the drinks industry, refillable plastic bottles, more especially PETbottles, in which the number of refillings is limited, are beingintroduced more and more instead of glass bottles. Such refillableplastic bottles must therefore be discarded if the number of round tripshas reached the limiting value. This, on the other hand, necessitatesthe plastic bottles being provided with at least one new code symbolbefore each round trip, and therefore with each filling, so that thenumber of round trips can be determined from the total number of codesymbols. The process and the device which are known from theabovementioned DE-OS 30 32 520 are not suitable for this, as thecontainers which are to be marked with a new code symbol are merelyseparated in each case, in order to be marked with a new code symbolelsewhere. Moreover, in the case of plastic bottles it would bedesirable to increase the data content beyond the mere number of codesymbols. In the case of bottles, this causes greater difficulties thanwith kegs, as the latter have a considerably larger diameter andtherefore more space for the code than bottles.

A code symbol is known from DE-OS 39 14 440. This describes an opticallymachine-readable binary code and also a process for creating it and fordetermining its size and density. The code is formed from a chequerworksymbol which reproduces the data in the form of black and white squares.The binary code is dynamically variable in its size, its format and inthe density of its data. The matrix has a periphery in which the dataare contained. The periphery is provided with a density display fordisplaying the density of the data in the matrix. By using the densitydisplay and a dimension display, a scanning device can calculate thesize and the data density of the binary code. This known binary code isnot suitable for refillable containers such as, for example, plasticbottles, because it would not be possible to accommodate on the lattereither a chequerwork matrix of black and white squares or an adequatenumber of such binary codes which are of an adequate size, so that thesquares can also be sufficiently reliably detected.

SUMMARY OF THE INVENTION

The problem of the invention is to modify a process and device of thetype hereinbefore mentioned in such a way that the code symbols can beread and the refillable containers marked with a new code symbol in oneoperation, without firstly having to be separated, and wherein there isalso intended to be a possibility of the data content of all the codesymbols containing more than just their quantity. Here, the code isintended to be arranged so that it can be easily read and applied, andmore especially, be space-saving. A corresponding code symbol isfurthermore intended to be provided.

The problem is further solved according to the invention, with adetection station having a combined detection and reading arrangementtogether with an image processing arrangement and code marking device,originating from apparatus of the type hereinbefore mentioned.

The apparatus simplifies the marking of refillable containers with codesymbols, as no special position marking is applied to the container, butthe already existing code symbols are used in each case for this. Thedata content of all the code symbols is larger than in known processes,as the code symbols are not applied to the container at arbitraryintervals and in an arbitrary sequence, but in a definite relation tothe previously applied code symbols in each case. This further allows aspecially space-saving arrangement of the code with good readability.The apparatus requires less expenditure of time for marking, ascontainers which are to be marked are not separated, but are also markedwith a new code symbol in the same operation after reading. The codesymbols form a regulated sequential code, as the application of the codeand the interpretation of the code are a function of the relativeposition in regard to a reference point, and if, as explained further ingreater detail, a suitable code symbol is used, are a function of therelative position of the code elements or words.

The apparatus in comparison with the known apparatus, offers the sameadvantages, as the detection and reading device are combined together,and a marking device for marking the containers with code symbols isconnected to the latter inside one and the same apparatus.

The subject matter of the subsidiary claims relate to advantageousdevelopments of the invention.

The first code symbol is advantageously not randomly positioned, but independence on a code sign of the manufacturer's code.

In one development of the invention, the position for applying a newcode symbol linked to the code symbol applied during the precedingrefilling can be found in a specially simple and error-free manner, asthe angle between this position and the first code symbol of themanufacturer's code through which the container has to be rotated aboutits axis of symmetry during the movement out of the detection andreading position into the marking position, is determined in each case.

The reading reliability is increased and the marking is simplified if inone development of the invention, each new code element is inscribed ina cell, i.e. in the next free cell, the inscription occurring in such away that the code symbols do not mutually overlap.

The invention offers the special advantage that there is formed on thecontainer not only a round trip code, but with the aid of the datacontent of the latest available code symbol in each case, the history orthe past of the container can be followed, in regard to filling and/orbottler and/or filling date and/or other data concerning the refillingof the container. Here, the data concerning the filling which has beenin the container in the past and more especially recently, is of greatimportance in the case of plastic bottles. Plastic such as, for examplePET, does in fact absorb odour from the filling. Also, the latter cannotbe removed by the washing of such bottles, because plastic bottles haveto be washed at considerably lower temperatures than glass bottles, eg.at only 50° to 60° C. If a plastic bottle is provided as a multi-purposebottle which is intended to be filled with four different drinks, eg.with mineral water, lemonade, fruit juice and a cola drink, it isadvantageous to adhere to a permitted filling sequence during refilling.A permitted filling sequence would, for example, be to fill a plasticbottle which was previously filled with mineral water, with a coladrink. On the other hand, an inadmissible filling sequence would be tofill a plastic bottle which was previously filled with a cola drink,with mineral water. In the development of the invention, it is possible,by evaluating the data content of the recently existing code symbol, toseparate a container if a permitted filling sequence were not to beadhered to as a result of the refilling.

Another development of the invention provides a specially simplepossibility of marking plastic bottles with code symbols. The processfor coding by means of a laser beam and its control by a mask or a gateor modulation by a beam-deflection system are the subject-matter ofGerman Patent 38 29 025 of the applicant, to which reference is madeconcerning further details.

A further development of the invention guarantees good process results,as a reliable camera technique and also image-processing hardware andsoftware are available. As an example, reference may be made to an olderproposal of the applicant which constitutes the subject matter of GermanPatent 40 27 992, to which reference is made concerning further detailsin like manner.

An apparatus employing a variable matrix is especially suitable forbeing able to trace the past or history of a container. The size of thematrix elements within the code symbol can be selected in dependenceupon and according to code data content and configuration, position ofthe code symbol and/or reading process and/or according to otherdetails, as long as the size of the individual matrix elements is alwayssufficient to ensure a reliable perceptibility when the usual patternrecognition technique is used.

In further development, the apparatus is especially efficient, as thecarousel device makes possible a high throughput with accuratepositioning of the containers in the detection and reading station andalso in the marking station, and the use of only one camera, or only onemarking device, in these stations. The carousel device makes shortmanufacturing times possible, because the containers during the time inwhich they are moved out of the detection and reading station into themarking station are moved about their own axis of symmetry into theposition in which they have to be marked with the new code symbol. Themovement out of the one into the other station is no lost time, as afterthe detection of the relative position of the manufacturer's code andthe round trip code, the container has to be rotated in any case intothe position which is suitable for marking with the new code symbol, andthis rotation now occurs during the movement between these two stations.The marking process itself likewise proceeds very rapidly, becausealways only a single code symbol is put on the container per refilling.

In the development another rotation device makes it possible to positionthe containers in the two aforementioned stations in a manner which isaccurate and gives little vibration.

In the development of a further invention the code symbols and themanufacturer's code are in the areas of the container which are lesssubject to mechanical damage during handling, such as, for example, thecurved wall area of a plastic bottle immediately above the base. Insteadof this area, an area on the neck of a plastic bottle can also be used,but the available space here is considerably smaller on account of thesmaller diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplified embodiments of the invention are described hereafter withreference to the drawings, in greater detail.

FIG. 1 shows apparatus according to the invention for marking refillableplastic bottles,

FIG. 2 shows the apparatus according to FIG. 1 in a simplified top planview,

FIG. 3 shows the apparatus according to FIG. 1 in side view,

FIG. 4 shows as a detail a head of a rotation arrangement of theapparatus according to FIG. 1,

FIG. 5 shows as a detail a rotatable seat of the apparatus according toFIG. 1 with a plastic bottle which is arranged on the seat and is onlypartly illustrated,

FIG. 6 shows a logic diagram for the apparatus according to FIG. 1,

FIG. 7 shows sixty-four possibilities of development of a code symbol,and

FIG. 8 shows diagrammatically the mutual association of manufacturer'scode and round trip code.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description actually relates to the marking of refillablecylindrical containers in the form of PET bottles (hereinafter referredto in brief as bottles), but other transparent or non-transparentcylindrical containers, eg. glass bottles or tin cans, can also bemarked with the device.

The apparatus is indicated in general by 101 in FIGS. 1 to 3. Theapparatus 101 has a frame 102 with an upper support plate 103 and alower support plate 104, between which is fastened a carouselarrangement indicated generally with 106. The carousel arrangement 106has a central carousel 108 with twelve receiver arrangements 110 forbottles 112 and also two smaller carousels 114 and 116, each with eightreceiver arrangements. The carousel arrangement 106 is part of aconveyor arrangement, with which the bottles 112 are moved into adetection station 130 and a marking station 140, which is described ingreater detail further on. The two smaller carousels 114 and 116, inconjunction with two screw conveyors 118 and 120, convey the bottles 112into or out of the apparatus 101. Below the lower support plate 104 isfastened a common drive system 122, which comprises a geared motor 124which drives the carousel arrangement 106 and the screw conveyors 118and 120 via toothed pulleys and toothed belts which are not indicated ingreater detail.

The central carousel 108 is composed of an upper main carousel 108a, acentral main carousel 108b and a lower main carousel 108c, which arefastened to a common shaft 109. The receiver arrangements 110 arecomposed of twelve cavities, semicircular in cross-section, on thecentral main carousel 108b, twelve heads provided on the upper carousel108a (only two are visible in FIG. 1) and twelve rotatable seats 128,mounted on the lower main carousel 108c, for receiving, clamping ormounting the bottles 112. One of the heads 126 is illustrated in FIG. 4as a detail to which reference is now made together with FIG. 1.

Each head 126 is fastened so as to be vertically movable on the uppermain carousel 108a. A support ring 134 is fastened to the upper supportplate 103 by means of screws 132. The support ring 134 carries anannular cam body 136, on the cam track 138 of which runs a followerroller 142, which is illustrated here as a ball bearing. The followerroller is fastened to the top end of a support rod 146 by means of abolt 144. The head 126 is fastened to the bottom end of the support rod146. A linear bearing 150 is arranged in a bearing housing 148 which isfastened to the upper main carousel 108a. Between the bearing housing148 and the head 126 there is arranged in a spring housing 152 a spring154, which preloads the head 126 in a downward direction. The head 126can at any time be moved downwards by the spring as permitted by theheight of a bottle 112 or the cam track 138. A pin 156, which isdisplaceably guided in the upper main carousel 108a, prevents the head126 in the linear bearing 150 being able to rotate about thelongitudinal axis of the support rod 146. At the outer end of the head126 is fastened a stepping motor 158, which via toothed wheel reductiongear 159, rotates a sleeve 160 which can be lowered with the head 126onto the bottle mouth. The sleeve 160 thereupon engages the bottle mouthwith a friction ring 162. The course or the shape of the cam track 138is so selected, that the head 126 is arranged in the area of thecarousel 114 at a spacing above the bottle mouth, then during themovement of the bottle 112 into the detection station 130, is loweredonto the bottle mouth and remains lowered at least until the markingstation 140 is reached, and is finally raised again from the bottle andmoved back to its original height, in which it is at a spacing from thebottle mouth. The control of the stepping motor 158, by means of whichthe bottle 112 can be rotated about its axis of symmetry, ie. itsvertical longitudinal axis, is described below.

The motor 158 of each head 126 is not arranged on the axis of thebottle, ie. not on the central axis of the sleeve 160, but at a spacingtherefrom, in order not to obstruct the line of sight for a detectiondevice which is also described in greater detail below. This detectiondevice comprises a camera 164 and an illumination source 166. Accordingto FIG. 1, the camera 164 is fastened to the underside of the uppersupport plate 103 beside the upper main carousel 108 and above the pathof the heads 126. The illumination source 166 is fastened to the bottomsupport plate 104 below the lower main carousel 108c in line with thecamera 164. The bottles are moved by the central carousel 108 on acircular path, and in the detection station 130 each bottle passesthrough a position in which its axis of symmetry coincides with the lineconnecting the illumination source 166 and the camera 164. This positionis illustrated on the left in FIG. 1 and also in FIG. 6. The lightingsource 166 is a stroboscope, which generates a flash of light each timea bottle 112 is exactly between lighting source and camera.

In FIG. 5 are shown the lower main carousel 108c and the rotatable seat128 as the bottom part of one of the twelve receiver arrangements 110 ofthe central carousel 108. The rotatable seat 128 comprises a circularpart 168 of transparent material (eg. acrylic glass), which is fastenedin a circular opening of the lower main carousel 108c, and of a platform170 for the bottle 112, which is rotatably fastened in the annular part168 in the manner illustrated in FIG. 5. The lighting source 166 sendslight upwards through the transparent annular part 168 and illuminatesthe bottom curved part 112a of the bottle. In this area the bottle 112carries a manufacturer's code MC which is present from the beginning,and a round trip code TC, which is already applied or has still to beapplied. The manufacturer's code MC is composed of several code marks,and the round trip code TC is composed of at least one code symbol, allof which is described in greater detail hereafter. The camera 164 takesa picture of the lower area 112a of the bottle 112 from the inside ofthe bottle when the latter is illuminated by the lighting source 166. Asan instantaneous exposure is involved, the carousel arrangement 106 doesnot need to be arrested in the detection station 130. On its way to thedetection station 130, the bottle is clamped by the head 126, which ismoved vertically downwards onto the bottle mouth and which pressesagainst the bottle mouth (in the case of PET bottles, the ring aroundthe outside of the bottle mouth) and at the same time presses the bottleagainst the freely rotatable platform 170. As soon as the camera 164 hastaken a picture of the lower area 112a, the stepping motor 158 causesthe bottle 112 to rotate so that when it reaches the marking station140, it has been rotated about its axis of symmetry into a position inwhich it can be marked with a new code symbol of the round trip code TCby a marking device 172 provided in the marking station, in the mannerdescribed in detail hereafter. The marking device 172 in the exemplifiedembodiment illustrated is a laser which sends the laser beam obliquelyfrom below at an angle of about 38° to the horizontal (centre line CL ofthe round trip code TC) onto the outer surface of the bottle 112. Thelaser beam can be sent through a device 173, in order to give the codesymbol a certain configuration. The device 173 can be a mask, a gate orthe like, or a beam-deflecting system which modulates the laser beam.

FIG. 6 shows a diagram of a logic apparatus which is marked generallywith 174. This comprises a main controller 175, an image processor 176and a carousel microcontroller 177 as a control device for the twelvestepping motors 158. The carousel microcontroller 177 has twelve outputsA1-A12 for the stepping motors 158, but only one stepping motor 158 isshown in FIG. 6. The main controller 175 is mounted beside or at adistance from the apparatus 101, whereas the carousel microcontroller177 is fastened to the lower main carousel 108a, as indicated in FIG. 1.Its outputs A1-A12 are connected to the stepping motors 158 viaunillustrated lines. The connection between the stationary imageprocessor 176 and the carousel microcontroller 177 rotating with thecentral carousel 108 is obtained through a slip ring 178. The latter, asindicated diagrammatically in FIG. 6, has a stationary slip ring 178aand a slip ring 178b, which is fastened to the shaft 109 of the centralcarousel 108 and therefore rotates. Data are transmitted serially duringthe relative rotation of the slip rings.

The main controller 175 follows the bottles 112 on their way through theapparatus and thereby receives input signals from various sensors and arotary sender (not illustrated in each case) and thus controls theentire apparatus including the actuation of the lighting source 166 andof the camera 164, which are likewise part of the image-processinghardware. The image processor 176 determines the position of theoriginal, ie. the first code mark of the manufacturer's code MC and ofthe first code symbol of the round trip code TC relative to thereference system of the receiver arrangement 110 and also the number andthe data content of the code symbols of the round trip code alreadyfixed. The carousel microcontroller 177 determines, in a manner which isto be more fully described hereinafter, the position of the place wherethe new code symbol is to be fixed, in which connection it uses datafrom the image processor, and positions the bottles in such a way thatthe new code symbol of the round trip code can be fixed at the correctplace by means of the laser 172. To this end, the carouselmicrocontroller 177 controls the stepping motor 158 of the head 126which is in the detection station 130, so that the stepping motor 158rotates the bottle accordingly, until it reaches the marking station140.

Each bottle has to be provided with a new code symbol of the round tripcode, if this is permissible for the reasons explained hereinafter ingreater detail and the bottle does not have to be discarded. A rejectionmeans 180 is merely indicated symbolically in FIG. 2. It may be anozzle, which blows against the bottle which is to be discarded.

The apparatus for marking refillable transparent bottles operates, onceagain briefly summarised, in the following manner.

After the bottle 112 has passed the screw conveyor 118 and the carousel114 at the inlet of the device, it is vertically clamped in the receiverarrangements 110 of the central carousel 108 by lowering the head 126.After clamping, some time is available to allow any vibration to dieaway. The bottle 112 then passes the detection station 130, in which thecamera 164 (above the bottle) and the lighting source 166 (below thebottle) are provided. The camera 164 takes a picture of the lower area112a of the bottle 112, where the codes MC and TC are situated. Theimage processor determines the position of the original of the codes andthe number of existing code symbols of the round trip code TC (eg. inapproximately 120 ms). This data is transmitted to the main controller175 and from here to the carousel microcontroller 177. The carouselmicrocontroller 177 controls the stepping motors 158, in order to bringthe bottle 112 into the position in which it can be marked with a newcode symbol (which requires less than 240 ms, for example). Variousstrategies can be followed for the course of the speed of rotation overthe time in dependence upon the number of rotational steps to beperformed by the stepping motor 158, in order to avoid vibration, tolose no rotational steps and to carry out the movement in the timeavailable between the detection station 130 and the marking station 140.The movement here is supervised by an unillustrated inductive proximitysensor. When the bottle 112 has been correctly positioned for applyingthe new code symbol, the place at which the new code symbol is to beapplied is exactly on the centre line CL of the laser 172, which thenacts upon this place. After applying the new code symbol the bottle isreleased, by raising the head 126. The carousel 116 and the screwconveyor 120 at the outlet of the apparatus 101 convey the bottle 112out of the apparatus.

Further possibilities which are offered by the main controller 175 andthe carousel microcontroller 177, such as statistics, self-testing,programming of the various types of operation etc., are not necessaryfor an understanding of the invention and for this reason do not need tobe described in greater detail here. On the other hand, the purpose ofthe round trip code, whose compilation (mechanical appearance) and theprinciples and process for applying and reading the round trip code,which is engraved on transparent refillable bottles, are important forunderstanding the invention, for which reason this is describedhereafter in greater detail.

It has already been explained hereinbefore, that the main purpose of theround trip code TC is to be able to trace the history or past of thebottle regarding filling and/or bottler and/or bottling date and/ornumber of fillings and/or other data concerning filling. The round tripcode is an organised, sequential code and contains thirty or more dataparts, each of which has a range of 2048 or more possible combinations,which in the manner described here, are engraved in the surface of atransparent bottle and are later read again.

According to the illustration in FIG. 7, the round trip code TC has thefollowing features:

1. A variable 3×3 matrix with binary rough data from 2⁹ =512 differentcombinations.

2. A fixed 3×1 line vector, which is arranged on the top or bottom (orboth) of the matrix, for class discrimination and for the registrationprocess during reading and interpretation.

3. A fixed 3×1 column vector, which is arranged on the left or rightside (or both sides) of the matrix, for class discrimination and for theregistration process during reading and interpretation.

4. An error detection and/or correction mechanism for each line and/orcolumn (eg. a CRC code, a Hamming code, odd/even parity etc). Each ofthe above components of the code may or may not exist in one codesymbol, as shown in FIG. 7.

Each code symbol of the round trip code TC can be applied to refillablecontainers and more especially to refillable PET bottles at variouspoints. Areas which are less subject to mechanical damage caused byhandling and use are preferred, such as, for example, the curved area112a (FIG. 5).

Each element of the code symbol (ie. a matrix element, a vector or atesting element) has a size within a range of 0.5 to 2.5 mm, dependingupon data content/configuration of the code symbol, fixing point of thesame and/or reading process and/or other factors to be considered,resulting in an overall size of each code symbol which ranges from 2 to13 mm×2 to 13 mm, which is dependent upon the same influencing factorsas in each element.

The round trip code TC is denoted as ordered and sequential, as theproduction and the interpretation of the code are a function of theabsolute and/or relative position with regard to a reference point and afunction of the relative position of the code elements (words).

The round trip code TC in the example described here is engraved in theouter surface of the bottle 112 by means of the laser 172. Reading ofthe round trip code TC and interpretation of the data content occur bymeans of the abovedescribed image-processor hardware and software usingthe camera 164.

The code symbol 1 in FIG. 7 contains merely the column and line vectoras a registering marking (for maintaining registration during readingand interpretation of the round trip code). The usable surface of thecode symbol is the rectangular-shaped 3×3 matrix, which makes possiblean alphabet of 4 symbols and words of 3 symbols in each case, producingaltogether 4³ =64 possible code symbols.

By way of example, the 64 code symbols can be coordinated with 16filling installations, each of which is able to fill the bottles with 4different products. The coordination can occur in the following way:

Code symbol 1: Installation 1, product 1

Code symbol 2: Installation 1, product 2

Code symbol 4: Installation 1, product 4

Code symbol 6: Installation 2, product 2

Code symbol 11: Installation 3, product 3

Code symbol 16: Installation 4, product 4

Code symbol 63: Installation 16, product 3

Code symbol 64: Installation 16, product 4.

Another possibility of coordination could consist of coordinating 64different products with 16 installations, eg. products 1 to 4 frominstallation 1, 5 to 8 from installation 2, 9 to 12 from installation 3,. . . and 60 to 64 from installation 16.

The round trip code TC in the example described here is fixed to thebottles 112, the manufacturer's code MC, which has already been inexistence on the bottles from the outset, being referred to for thechoice of the reference marking. The manufacturer's code MC is engravedin the bottle when it is manufactured (or fixed in another way) andcontains data concerning the manufacture of the bottle (working shift ofthe bottle manufacturer, type of bottle, bottle production line, date,control bits, start and stop bit). An appropriate manufacturer's code ofthe applicant which is used with PET bottles is composed of 32 bits, butit is not necessary to consider this more closely here.

The round trip code TC is composed of a succession of code symbols, ofwhich one is applied to the bottle during the first filling and furtherones during each refilling, and therefore consists of at least one codesymbol and of a maximum of 25 to 30 code symbols. Each code symbolcontains data concerning the filling and the bottler.

The manufacturer's code MC and the round trip code TC are arranged inthe basal area 112a of the bottle in closely adjacent circular rings(FIG. 5). The radius one which the centre of the first bit of themanufacturer's code is situated is regarded as the origin of the code.The circular ring, ie. the circular ring-shaped surface area in whichthe round trip code TC is applied, is divided into 25 cells (in the caseof bottles in which 25 round trips or fillings at maximum arepermitted), so that each cell occupies 360°/25=14.4°, that is to say,from the aforementioned origin (source), which is illustratedsymbolically in FIG. 8. Each new code symbol is inscribed in the firstfree cell. The first code symbol TC is preferably placed underneath thecode mark MC1, as shown in FIG. 8. The first code symbol can, however,also be placed randomly.

In order that no additive positioning errors can occur, the positionwhere the new code symbol of the round trip code is fixed is determinedwith reference to the origin (and therefore here with reference to thefirst code symbol in FIG. 8) and not with reference to the precedingcode symbol. Because the positioning accuracy is limited, the codesymbols of the round trip code TC do not occupy the entire cell in eachcase, in order to avoid overlapping.

It is advantageous, but not absolutely necessary, to use the first codemark MC1 of the manufacturer's code as a position marking for the codesymbols of the round trip code TC. For example, the second, third or anyother code mark of the manufacturer's code could also be used for thispurpose.

The mutual relative position of manufacturer's code and round trip codeis determined and known according to choice of the position marking.When the bottle 112 passes into the central carousel 108, it has anoptional position in relation to an external reference point. The imageprocessor 176 therefore determines firstly the position of themanufacturer's code and the round trip code which already exists in somecases. Thereafter, the image-processing software can determine in asimple manner, the angle through which the bottle has to be rotatedabout its axis of symmetry on its way to the marking station 140, sothat the correct place for the new code symbol is then situated in thecentre line CL of the laser 172. The image processor here determines theposition of the round trip code TC and the number of cells alreadyoccupied by code symbols of the round trip code, in order to find thefirst free cell in which the new code symbol has to be inscribed. Ifthere is not yet any code symbol, the position of the first code isselected at random, but preferably in dependence upon the position ofthe manufacturer's code MC.

It has already been fully described hereinbefore, that a new code symbolis fixed only when a certain filling sequence is adhered to byrefilling. The data necessary for this is obtained by the imageprocessor 167 by evaluating the data content of the last code symbol ofthe round trip code TC in each case. This data is contained in theindividual code symbols 1 to 64 in the way described above, in whicheach code element is composed of one, two or three matrix elements whichadjoin each other vertically without gaps. Of these code elements, zero(see code symbol 1) to three per code symbol may exist (see code symbol64) and consist of 1 to 3 matrix elements in each case, which canreadily be seen from FIG. 7 and the coordination example stated above.

In the exemplified embodiment described hereinbefore with reference tothe drawings, the camera 164 is provided in the detection station 130not only for detecting the manufacturer's code MC, but also for readingthe round trip code TC. If an inspection machine with a camera isalready in existence in a filling plant, which operates according to theprinciple of the camera 164 described here (that is to say, as a videocamera with CCD or similar image converter device), the manufacturer'scode which exists from the outset on the bottle, is stored in the memoryof the inspection machine with the image of the lower area of thebottle. This stored data can be used in the image processor 176, inorder to find the absolute position of the manufacturer's code formarking with the round trip code, if this is preferred for the firstcode symbol. In this case, merely a photodetector needs to be providedin the detection station 130 instead of a camera. The photodetectorreads the bit pattern of the manufacturer's code, which pattern iscompared with the manufacturer's code bit pattern which is fed in fromthe memory of the inspection machine and is also known. The trueposition of the manufacturer's code is found when the number ofnon-correspondences between the stored and the read bit pattern is atthe minimum. From a code mark of the manufacturer's code selected as aposition marking, the photodetector also reads the code symbols of theround trip code. Reading of the data content of the code symbols takesplace in the image processor by corresponding pattern-recognitiontechnology.

We claim:
 1. Apparatus for marking refillable containers, having amanufacturer's code, which defines a reference position on thecontainer, and code symbols with the aid of which it can later beascertained whether a container has to be refilled or separated,comprising:a conveyor for moving the containers in a conveyingdirection; a detection station positioned along the conveyor, and havinga combined detection and reading arrangement with a camera forphotographing manufacturer's codes and code symbols on the containers; aprocessing arrangement with an image processor connected to the camerafor determining the positions of the manufacturer's code and the codesymbols on the containers; a rotary device for rotating the containersabout an axis of symmetry, a controller connected to the image processorand to the rotary device to rotatably position the containers formarking relative to the manufacturer's code, and a marking stationpositioned along the conveyor and having a marking device for markingthe containers with code symbols indicative of the number of times acontainer has been refilled and positioned on the containers inreference to the positions of the manufacturer's code and any other codesymbols previously-marked on the container, the marking station beingpositioned after the detection station in the conveying direction. 2.Apparatus as claimed in claim 1, wherein the conveyor furthercomprises:a carousel device with several receivers for the containers,wherein each of the receivers is coordinated with the rotary device forrotating a received container about its axis of symmetry and eachreceiver can be moved one after the other through the detection stationand the marking station.
 3. Device as claimed in claim 2, wherein eachrotary arrangement has a head which is movable along the axis ofsymmetry, and which can be lowered onto the container by means of acurved body, and carries a stepping motor which can be actuated by thecontrol arrangement and is mounted laterally to the axis of symmetry ofthe container, said motor being arranged to rotate the container aboutthe axis of symmetry, and that the carousel arrangement has an uppermain carousel, on which the heads are mounted.
 4. Device as claimed inclaim 1, wherein the marking device has a laser and the laser isarranged to form the code symbols on the container in a circular ringaround the circumference of a bottle in a predetermined positionrelative to the manufacturer's code.